Commercially available semiconductor structures can include wafers, such as bulk silicon or silicon-on-insulator (SOI) wafers. On such wafers there can be formed one or more type of device such as a field effect transistor (FET).
Semiconductor structures can include isolation regions that separate active device regions of the semiconductor structure. In some commercially available arrangements for example, an isolation region can separate a first active device FET region from a second active device FET region. A first active device FET region can be an nFET region having nFETs and a second active device FET region can be a pFET region having pFETs. In some cases isolation regions can include trenches. Various methods are used for formation of trenches. According to one known method, lithography techniques can be used for patterning trenches. Formed isolation region trenches can be filled with dielectric material, e.g., oxide.